Synonyms of impregnable in English:

impregnable


See definition of impregnable

adjective

1‘such a castle must have been impregnable’

SYNONYMS
invulnerable, impenetrable, unattackable, unassailable, inviolable, secure, strong, stout, safe, fortress-like, well fortified, well defended
invincible, unconquerable, unbeatable, indestructible
ANTONYMS

vulnerable

2‘an impregnable parliamentary majority’

SYNONYMS
unassailable, unbeatable, undefeatable, unshakeable, invincible, indomitable, unconquerable, unstoppable, invulnerable
ANTONYMS

vulnerable

3‘as a working theory, this is impregnable’

SYNONYMS
irrefutable, incontrovertible, undeniable, indisputable, incontestable, unquestionable, unassailable, beyond question, beyond doubt, indubitable
flawless, faultless, watertight, airtight, foolproof, without loopholes
ANTONYMS

flawed